relay help with new engine

bryanjeep · #1 (**permalink**) 02-26-2004, 08:50 PM

Here goes,
When I rewire the Jeep for the new engine, I am looking to run all my ignition hot parts through a relay system. ( carb choke, gauges, fan, radio, stock fuel pump, distributor, and 700r4 electric part). I am trying to get away from having to run relays for each of these parts. Is there one big powerful relay that I can buy to run them all and not have worries? What kind of setup do you recommend?

White · #2 (**permalink**) 02-26-2004, 08:57 PM

I have looked for several heavy duty contactors. The best i have found for offroad lighting was the starter relays from fords. I dont recommend the use of them, Iam just not sure how reliable they are.
But they will handle real heavy loads.

XJNick · #3 (**permalink**) 02-26-2004, 09:57 PM

Hi,

A high rated relay I know of for automotive applications is made by Bosch Part # 0 332 002 156. It switches up to 75 amp loads.

If you need a load greater than 75 amps switched, you'll have to move up to using D.C. Contactors (not solenoids!). There is a whole line of high amperage (~80 - 400 amps) DC contactors made by Curtis/Albright.

A really good source for the Bosch relays and many other electrical components is Waytek wire at www.waytekwire.com

Be sure to protect a high amp relay circuit with a proper circuit breaker or High amp fuse, too.

As a last note, realize that it is ok to have certain loads running through the ignition switch. it is designed to switch quite some power. For example, things like the gauges, radio, engine control system, etc. are perfectly safe to pull through the switch. It is your call, but using relays for everything isn't always the best solution

-Nick

derff96963 · #4 (**permalink**) 02-26-2004, 11:59 PM

Well the only real problem I see with this would be if you have a problem like a short in one of the systems you may loose everything. For example if wiring to light shorts out you will blow your main fuse and loose everything and if for some reason it doesn't blow the fuse it can melt the wire and cause an eletrical fire. I know you want to make it easier to rewire. If it was a good idea I bet jeeps would have been that way from the factory. I just don't think its a good Idea.

Snitty · #5 (**permalink**) 02-27-2004, 02:43 AM

well, you can always fuse every circuit from that main relay... then if one shorts, it only pops its own fuse

bryanjeep · #6 (**permalink**) 02-27-2004, 06:04 PM

So it seems like you recommend running 1 maybe 2 relays for the system. Sort of even out the power between the two relays. I just need to make sure that I get a powerful relay. How much do they cost me?

XJNick · #7 (**permalink**) 02-27-2004, 10:32 PM

Hi,

Quote:

you recommend running 1 maybe 2 relays for the system

No, I actually do NOT recommend doing this.

The main reason being what was mentioned earlier in this thread, which is you'd be talking a risk. First, think about what would happen if the 1 or 2 relays unlatched/shorted/ or failed. You'd be driving and suddenly loose power to everything, most importanty the engine control system(s).

However, I was providing you with the link to Waytek Wire so you could see that the larger power relays Do exist if you decide that is what you want to do. I believe the Bosch one I mentioned earlier was around $10.00 or so. Be ABSOLUTELY sure you also buy a 75 or 80 amp fuse or circuit breaker to install upstream of this relay! Simply adding fuses to every "branch" ciruit the relay powers is Not suffiecient. You Always need a fuse/breaker upstream of a relay.

Anyways, I recommend running all the engine control system circuits through the ignition switch Without a relay. Same thing with things like gauges, radio, etc. Don't be afraid to power lower-amperage items straight through the ign. switch, it won't hurt it.

Do run things like winch, fuel pump, fog lights, A/C compressor clutch, radiator fan, etc. through relays (not all the same one) as they pull enough power that you'd not want them through the ign. switch

-Nick